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Dow Jones industrial average ditches Exxon, adds tech names in biggest overhaul since 2013
A Mobil gas station. Carlos Jasso/Reuters The Dow Jones industrial average will ditch a long-standing energy giant and tilt further toward tech stocks in its biggest shakeup since 2013.The 30-stock index will replace...
Dropping Unused Indexes on an Azure SQL Database
Index Maintenance is an important aspect of database health. Above and beyond regular index rebuilds and reorganizations it is important to understand the usage of the indexes on your database. Cleaning up unused indexes can save a lot of overhead on Insert/Update/Delete operations. To achieve that goal, I typically run a script like the one shown below and check out whether or not an index has had any seeks or scans against it as a...
SQL Server million level database optimization scheme
1. In order to optimize the query, we should try to avoid full table scanning. First, we should consider building indexes on the columns involved in where and order by. 2. Try to avoid null value judgment on the field in the where clause, otherwise the engine will give up using the index and scan the whole table, such as:select id from t where num is null You can set the default value 0 on num to ensure that the num column in the...
Magic MySQL performance analysis artifact of SQL → explain, the cornerstone of SQL takeoff!
Preface a moment of fun Someone raises a pig and wants to let it go. But the pig knows the way home and comes back several times. One day, the man thought of a tough way. He drove the pig around the mountain and let...
Technology sharing | InnoDB handler | read * variable interpretation
Author: Gao PengAt the end of the article, there is his book “in-depth understanding of MySQL master-slave principle 32”, in-depth understanding of MySQL master-slave, gtid related technical knowledge.Source version: percona 5.7.14This is a learning record. Please understand if there is any mistake. In this paper, it is recommended to watch on the PC side, with better effect. 1、 The essence of...
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JQuery operation select drop-down box
Get text and value selected by select $(“ා” select “Id”). Change (function() {/ / code…}); / / add an event for select and trigger when one of the items is selected Varchecktext = $(“” select “Id”). Find (“option: selected”). Text(); / / get the selected text Varcheckvalue = $(“” select “Id”). Val(); / / get the value selected by select Var...
